The Case for Christ documentary is based on a 1998 book by atheist author Lee Strobel who tried to prove his wife's Christian faith.
To make the case Strobel interviewed a number of respectable scholars to find out whether the resurrection of Christ was actually true and if the accounts made in the new testament could be made historically proven. Even though he was an Athiest he conducted all of his research without bias and draws conclusions only from the evidence found.
Interestingly after completing his mission Strobel became a Christian which inspired him to put together the information into a book. This documentary by American independent filmmaker Jon Gunn dramatises The Case for Christ book and features Lee Strobel himself.
Ultimately you have to make what you want from the evidence presented. Never the less it will be an interesting watch no matter if you are atheist, Christian or agnostic.